FFT Splitting for Improved FPGA-Based Acquisition of GNSS Signals

Figure 2

Illustration of the problem due to a transition coming from the secondary code or the data. The values in the boxes indicate the chip number. (a) The incoming primary code starts with the first chip; the correlation at the correct alignment is maximum, as it would be without data or secondary code. (b) The incoming primary code does not start at the first chip (usual case); the correlation at the correct alignment is reduced. (c) In the worst case, the incoming primary code starts at the middle of a period; the correlation at the correct alignment is very close to 0.

(a)

(b)

(c)